1. Field of the Invention
This invention relates generally to sensing and display equipment, and more specifically to fire detectors and emergency safety devices.
2. Description of the Prior Art
Fires and other emergencies can create critical escape problems for the occupants of buildings. For example, it can initially be difficult for an occupant to determine if a remote fire has even started, especially in a multi-story building. Once underway, however, such a fire can fill the rooms and hallways with smoke, making it then difficult for the occupants to find a safe exit.
Accordingly, numerous sensing and display devices have been developed to alert building occupants to such dangers, and assist them in their escape. For example, most modern building codes require prominent exit signs to be posted near all building exits. Other signs utilize a series of slightly raised "bumps" or other tactile reference to indicate exit direction in no-light conditions. These, of course, provide no fire alert or other warning, but at least they serve to generally identify an appropriate exit in an emergency. In addition, most buildings now incorporate fire detectors and smoke alarms as fixed, strategically-placed ceiling-mounted devices that emit a warning alarm when heat and/or combustion gasses are sensed. Some such devices also provide emergency lighting when activated. Unfortunately, the warning alarm is an alert only and provides no guidance to an exit, and the emergency lighting may be diffused or completely blocked out by dense smoke.
Other, more sophisticated systems provide a network of remote sensing devices in communication with a central monitoring unit. For example, in Topol et al. U.S. Pat. No. 4,531,114, when a fire is detected by one remote sensing device, and confirmed by another, the central unit can direct the remote devices to illuminate the building's exit lights and initiate speech-synthesized verbal exit instructions to the building occupants. However, such a system relies on a pair of remote warning devices to be activated, and on the central unit for control, and thus requires extensive, and costly, communication links. Even if the remote devices were to stand alone and operate independently, they would only serve to illuminate the building's exit locations, and would not provide any auditory support.